The Measure of All Things

by Ken Alder

  During this respite Méchain poured out his overburdened soul. Here at last was a sympathetic ear, as well as a knowledgeable astronomer. Méchain called Slop a kind of father, though he was only four years older. Virtuous, honorable, generous, good, venerable, worthy, with a noble simplicity of heart, and a bounty of wise counsel . . . , there was no end to the virtues Méchain ascribed to Slop, who practiced astronomy in Galileo’s former haunts. Slop had married a lively woman of English descent, Elizabeth Dodsworth, and they had raised their three children in an atmosphere of tolerance and freethinking. Francesco, the eldest, had been arrested the year before for dabbling in revolutionary politics. Now he was back in Pisa, supposedly working on astronomy.

  His stay with Slop’s family reminded Méchain how much he missed his own virtuous wife and children. Yet this recollection was a bitter one, for in the same breath he also remembered how he had abandoned them to all the dangers of Revolutionary Paris. The contrast, he confessed to Slop, was painful. “I will tell my wife and our children that if they desire happiness they should pray that heaven aid my efforts to resemble a husband and father as respectable as you, so tenderly dear to his own family and to all those who have the advantage of knowing him.”

  Méchain told Slop everything: his honorable motives for undertaking the mission, his unexpected misadventures along the way, his modest triumphs thus far, his growing frustrations with his assistants, even his tormenting doubts about the latitude measurements of Mont-Jouy and Barcelona. As a fellow astronomer, Slop understood the niceties of celestial observation—and the myriad ways that science might go wrong—yet he would not judge the results with the same critical eye as Méchain’s French colleagues, so concerned for the exactitude of the grand mission upon which all their reputations, careers, and perhaps even their lives depended. It was safe to confide in Slop. “You are the only one to whom I can speak so intimately,” Méchain would later write, “my only friend, the most worthy, the most virtuous, the most respectable.” To be on the safe side, he also swore Slop to secrecy, and later asked him to burn the wrenching letters in which “I opened my heart to you, as to a father.” It helped too that Méchain could be confident these letters would not be opened by the agents of the French Revolutionary state or find their way across the Alps to his colleagues in Paris. When read through the inevitable fog of self-deception, these letters offer a remarkable window into a man consumed by scientific doubt. In the days and weeks to come, he would confess his error at Mont-Jouy to Slop and to no one else.

  Méchain’s immediate goal remained Genoa. He considered making the voyage by ship, but ultimately set out instead with his team on the overland route, a two-day ride by saddle horse. The coastal road skirted the edge of mountains suspended above the sparkling Mediterranean. The terrain was rough, and the instruments traveled separately by coach, arriving undamaged in Genoa just one day after Méchain, Tranchot, and Esteveny rode into town on July 11. That very evening, Méchain dined with the French ambassador and dispatched letters to his colleagues in Paris to ask for instructions, to Slop to tell him of his safe arrival, and to his wife to inform her of his whereabouts. He told them he planned to return to France as soon as possible and that everyone had assured him that the mail boat to Nice was perfectly safe. Given his recent mishap at sea, however, he preferred to wait for official instructions. He had not heard from Paris in a year. He knew nothing of the status of the meridian project, his own status, or that of his family. No one back home even knew he had left Spain. Letters took at least a week to travel between Paris and Genoa and sometimes much longer; many never survived the trip at all, producing that tangle of unreliable and delayed knowledge which is the stuff of tragedy or farce, depending on the circumstances—or a gnawing anxiety, if one is that way inclined. Anticipating a delay, Méchain went down to the customs house to extract clothing and linen from his trunks, and settled into the Albergo del Leon d’Oro (the Inn of the Golden Lion).

  Genoa had once disputed dominion of the Mediterranean with Venice, and its vessels and bankers still traded from Gibraltar to the Levant. The spectacular semicircular harbor, with berths for scores of the largest vessels, formed an amphitheater at the foot of the Apennines. On a rocky promontory at one end of the harbor rose the spindly Lanterna lighthouse, like a Renaissance minaret four hundred feet tall. Most of the well-fortified town of 100,000 lived clustered near the harbor under blue slate roofs that mirrored the color of the sea. Strewn on the steep hills behind the town were sumptuous palaces and terraced gardens of orange trees. The prosperous city boasted an exquisite opera house and theater, plus plenty of street pageantry, from the annual San Giovanni procession to appease the floods of spring to the nightly promenade of elegant men and women along the ramparts. The nobles dressed all in black, with a short cape and no sword, and ruled the patrician republic as a tightly knit oligarchy. For the past century, however, the republic had been plagued by internal bickering, and French and Austrian armies had occupied the city in turn, obliging the patricians to trade the troublesome colony of Corsica to the French in order to preserve Genoa’s independence—this, two years before Napoleon’s birth on the island in 1769. Genoa still prided itself on its autonomy, and maintained a guarded neutrality as the French Revolution unleashed warfare across Europe. This neutrality pleased no one, of course. For the past year the English navy had intermittently blockaded the city. For his part, the French ambassador had been busy trying to incite the lesser nobles to challenge the ruling oligarchy, luring disaffected artisans to the French cause, and printing Jacobin propaganda in his basement. Meanwhile, eighty miles to the northwest of Genoa, the French army had attacked the Austrian and Piedmontese armies, according to the plan of a young general named Bonaparte.

  Indeed, three days after Méchain reached Genoa, Napoleon Bonaparte arrived there too. He had come on a “diplomatic” mission to urge the Genovese to ally themselves with France—or else. He stayed a week, covertly casing the town’s fortifications and assessing Italian politics. The upstart national republic was threatening to supplant the venerable city republic.

  GENOA HARBOR

  “Veduta di Genova” by Ippolito Caffi. (From the Galleria Internazionale d’Arte Moderna di Ca’Pesaro, Venice)

  While Méchain and his team waited for officials in Paris to decide their fate, the mail boat only brought word of fateful upheavals in the capital. On August 9—ten days after the event—report of Robespierre’s fall reached Genoa. For the moment, Paris was calm. Even this calm, however, could be variously interpreted. Tranchot hoped the radical cause would be regenerated now that Robespierre had been deposed. The engineer wrote to Francesco Slop, Giuseppe’s radical son, that despite the suppression of the Jacobins, “the same political order rules [in Paris] as it did before all these heads fell . . . , once again bringing despair to the aristocrats here who carry their head so high, but who will soon resume their usual bowing and scraping.” All across Europe, Tranchot boasted, French armies continued to advance. “Boisle-Duc is ours,” he noted, “as is Düsseldorf with its suburbs incinerated . . . , also the fortress of Coblenz, where the town will be razed the moment it falls into our power.” Closer to Genoa, the French army was bombarding Cúneo just eighty miles to the west.

  Tranchot did more than sympathize with the radicals. During his stay in Genoa, he operated in concert with the French ambassador and cultivated young Francesco Slop for the French cause. The two men shared the hope that the Revolution would come to Italy. Tranchot advised his young recruit to bide his time.

  I feel, as you do, the disgust of living out my life in a world for which you are not born. But you know as well as I that our revolution is not yet at that point at which a man should abandon the well-being he enjoys in his native country. That happy moment will come, however, and we may even hope that it will not be far off, for the basis for the new government seems gradually to be settling into a form which will inspire respect.

  Beneath this faith in the Revolution�
��s promise lurked a deeper pain. Tranchot had reason to believe that much of his family had been imprisoned or killed in the Revolutionary violence of his native Lorraine, a fact that must never be mentioned, Méchain told Slop, because his subordinate would “think it ill-intentioned of me to have let it be known.” Relations between the two men had deteriorated since their departure from Spain. Tranchot’s health was as robust as ever, and he was impatient for Méchain to order the expedition back into action. It was tedious to wait for official instructions from Paris. He had had enough of Méchain’s fastidious perfectionism, his endless second-guessing, and his refusal to allow anyone else to conduct observations, perform calculations, or even look in the expedition logbook.

  No word came from Paris that entire summer. Every Saturday the mail boat arrived with only the public newspapers in its satchel. As the weeks passed, Méchain grew anxious. “For a long time now I have been destined to languish in a state of uncertainty, destined to be tormented by the cruelest worries as to the fate of my family and the fate which awaits me.” These fears took many shapes. Had the meridian expedition been canceled? Might a jealous rival have denounced him to the Committee of Public Safety? It would not be difficult to make him appear culpable in their eyes: his long absence from France, his sojourn in countries hostile to the Republic, rumors that he had been offered a stipend and a position by the Spanish Crown, perhaps even whispers that his results were imperfect. No wonder he secretly asked Slop whether he might, if worse came to worst, seek refuge in some “obscure corner” of Pisa while he searched out a more permanent home for himself in exile.

  In mid-August, he finally heard from his wife. She informed him that the meridian mission had been suspended “at least until spring,” and that only the Committee of Public Safety had the authority to revive it. On the one hand, nothing now prevented him from returning home. On the other, he feared she was concealing even worse news from him. “Perhaps she only embellishes the state of affairs to calm me down for a few moments.” He poured out his doubts to Slop, professing his innocence, swearing his love for his family, and cursing his wretched luck.

  But forgive me; when I write to you I feel myself to be by your side, for it is the only moment when calm reigns in my heart. Oh, you know all too well what so cruelly torments and afflicts me. A virtuous, tender, and sensitive soul like yours feels all too well why I tremble as I approach my family, whereas under any other circumstances I would fly to them with transports of joy. It is the ardent desire to see them again which has made me break all my ties with them and separate myself for an indefinite period. Might not my return bring them new and more fearsome alarms; might I not trouble the little peace they now enjoy? How many frightening incidents and events will my return not present? May God not visit upon my family any of the harm which I might cause them.

  He bared his soul to Slop. “You are now reading, Monsieur, into the very depths of my heart. You see there the sources of that fear which so strongly agitated me when I was with you.” He doubted whether he was worthy of the friendship and counsel of so benevolent a man as Slop. He begged indulgence for his weakness. His health, he noted, had been deteriorating rapidly these past several months.

  Méchain’s spirits were not improved by the greetings sent by his colleagues on the Commission of Weights and Measures. At the end of August 1794 they finally sent him a copy of the law of August 1, 1793, which had established the metric system and which set the meter provisionally at 443.44 lignes. Moreover, they informed him that Delambre had been purged from the Commission, with no one assigned to take his place. Méchain drew his own conclusion: the meridian expedition, he decided, had been “definitively abandoned.” In which case, he had to wonder what purpose had been served by a mission “for which I have so tormented myself.” The little good he had hoped to accomplish had turned to ashes in his mouth, and his agony over the latitude of Mont-Jouy had become a bitter farce. “For it matters little now whether the latitude and longitude of Mont-Jouy be a quarter-minute too great or too little.” The new system of measures had already been established on the basis of the old measures of the meridian.

  All of which throws my spirit into the most extreme disgust. The ambition to be useful and win a little glory, which once animated me, turns out to have been a vain fantasy. What interest will my feeble labors inspire in the Commission or in the government when they no longer serve any useful purpose? Why then should I remain zealous to continue this mission? My attachment to my family? Oh, why have they set me on this course which has led me God knows where? Oh, if only I had chosen another path, the one which presented itself to me most naturally, I would today be at peace and sheltered from all reproach or suspicion. My work would be interesting to both [my colleagues and the government], and all would pity me. But I wanted to get the best out of this project, the best for my colleagues, and for myself, and it may be that with the purest of motives I will have brought about the unhappiness of my family and myself without having contributed in the least to the success of the mission, and without any hope of recognition. Well, enough of this; the more I think on it, the less bright the future seems. My lot is cast, I wait upon the event, and console myself with my conscience, secure in the knowledge that my actions have always flowed from the best of intentions.

  Yet the apparent cancellation of the mission, while it made all his labors meaningless, also brought a sense of relief: his measurements no longer mattered. If his efforts were to be buried in an unmarked grave, so too would their flaws. Indeed, the cancellation of the mission prompted Méchain to calculate how little difference his Catalan extension would have made to the estimate of the provisional meter. Now that the new standard had been set—albeit provisionally—what difference would his small addition make? “As you can see I add little, and any errors I committed in my small sector cannot have much influence, whether they cancel each other out or whether they are enormous; so that I am now trying to contain and calm the deadly disgust which is killing me.”

  Then, the very next week, came the good news that returned him to the depths of despair, plus some truly black news that nearly finished him off. His supposition had been premature: the meridian project was being revived. He heard it from his wife and from Lalande. General Calon had been placed at the head of the department of military topography, with Méchain appointed chief of naval cartography at an annual salary of 6,000 livres, two months’ of which had already been paid to his wife. Tranchot had received a subordinate position in the new organization. Official news of this appointment arrived from Calon himself two weeks later, with this request: that Méchain return immediately to Paris so that they might discuss the future of the meridian project together.

  As a practical matter, this promotion could only improve his family’s condition in the capital—where, his wife informed him, their provisions were running low—and it clearly gratified Méchain’s sense of self-worth. Yet he was not sure that a 33 percent pay hike would compensate for his added responsibilities. In his former humble job, he had only had to answer for the exactitude of his own work. Did he really wish to assume responsibility for the results of an entire department, conducted by men whose exactitude he could not vouch for? And how could he be sure this arrangement would outlast the next topsy-turvy twist of the Revolution? On top of this, Calon was ordering him to return to Paris, where he would surely have to turn over his data. “Oh, how well I see and feel why each man trembles for his own fate and for the interests that are dear to him, and why no one dares act.”

  Worse, the revival of the meridian project meant that his mistake mattered again, that the discrepancy in the Mont-Jouy data was once more an affront to the accuracy of the meter, “the most important mission with which man has ever been charged.” So many reversals seemed to have upended Méchain’s mind. He admitted to Slop that he could barely think straight any more. “In my last letter to you I importuned you with my guessed-at results, and you saw the dying efforts of a downed combatant who s
till fights for a victory and a success that long ago eluded him. In picking myself up, shamefaced and dispirited, I can barely remember what I was running from or what I said.”

  Most unsettling of all was the news that accompanied the announcement of the meridian project’s revival. Lalande confirmed that Lavoisier, Condorcet, and several other colleagues had been guillotined. Worse, Lalande informed him that the Terror had struck even closer to home—on the grounds of the Observatory, where his family still lived. Alexandre Ruelle, the young apprentice astronomer whom Méchain had taken under his wing, sheltered from the police, and trained for eight years, had denounced Cassini to the Revolutionary police, condemning his former protector to prison, and then capped his hideous betrayal by demanding that Cassini, Lalande, and Méchain be sent before the Revolutionary Tribunal and thence, inevitably, to the guillotine. Had Méchain been living in Paris at the time, the consequences would have been too awful to contemplate. At least Ruelle himself was now in prison—for his foul betrayal, for backing the radical party out of favor, and also for having committed a scientific error. Yet even after telling Méchain all this, Lalande still expected him to return to France that month.

  Méchain also heard from other voices, friends who had sought refuge from the Revolution overseas. They urged him to join them in exile, to give up all hope of rescuing his wife and children, to cease to serve a country which had bloodied itself so horrifically.

  [My friends] tell me I should count myself lucky if the Committee of Public Safety abandons me. They say that if the Committee spares my life, yet strips me of all my resources, exposing me to a thousand perils, that my wife, children, and I will come to seek death as the only way out of our misfortunes. They tell me that my return to Paris would do my family more harm than good. And they urge me, with great ardor, to follow them into exile. But my family, my duty, and my honor also call me, and I have always hearkened to their voices. Why should I repudiate them now . . . ? Why do such dire auguries traverse the seas to find me? Am I really so guilty?